RizonStrike vs probability: two ways to quote the same up/down contract
A cents market fixes the strike and moves the price; a strike book fixes the price and moves the strike. How to convert between them, with Bitcoin data.
Short answer: An up/down contract has two numbers, a strike and a price, and a market can fix either one. A cents market fixes the strike (the price to beat) and lets the price move: Up at 70¢ says the market gives Up a 70% chance. A strike book fixes the price and lets the strike move: on Rizon every contract costs its size and pays 2×, the equivalent of 50¢ for $1, and the book quotes the strike instead. They convert through the price distribution: over one minute of Bitcoin in October 2026, Up was worth 70¢ about $11 below spot, 50¢ at spot, and 30¢ about $11 above it.
Most prediction markets quote prices in cents, so that's what most traders learn first. Rizon quotes strikes, like a futures book. Neither is more correct; they answer the same question from opposite ends. This post shows how to move between the two, using a month of Bitcoin data.
The same contract, quoted two ways
| Cents market | Strike book (Rizon) | |
|---|---|---|
| What's fixed | The strike (the window's price to beat) | The price: every contract costs its size and pays 2× |
| What moves | The price of Up and Down, in cents (between $0 and $1) | The strike, in dollars |
| A quote means | "Up is worth 70¢": the chance the market gives it | "Up at $82,989": where traders will take the trade |
| A good trade is | Buying Up below what it's worth | Buying Up at a lower strike than you think fair |
| The spread is in | Cents | Dollars of strike |
| Ties at the strike | Settled by the venue's rule | A push on BTC: both sides get their size back |
In a cents market, a share pays $1 if it's right, so its price in cents is a probability: buying Up at 70¢ costs 70¢ to make 30¢. In a strike book, the payout is always 2×: buying up for $10 returns $20 if Bitcoin finishes above your strike and $0 if it finishes below. That's the same as buying a cents contract at exactly 50¢, every time. What you choose is where the line is.
Converting: what Up is worth at each strike
For every second from 27 September to 26 October 2026, we checked where Bitcoin was one minute and five minutes later, and counted how often it finished above a strike set $k from the starting price. That share is the fair price, in cents, of Up at that strike (ignoring fees and spreads).
Read it both ways. Pick a strike on the horizontal axis and the curve gives its price in cents. Pick a price on the vertical axis and the curve gives the strike that's worth it.
| Fair price of Up (¢) | 15 s contract: strike vs spot ($) | 1 min contract: strike vs spot ($) | 5 min contract: strike vs spot ($) |
|---|---|---|---|
| 90 | −17.08 | −37.41 | −85.61 |
| 80 | −8.01 | −20.80 | −48.80 |
| 70 | −2.10 | −11.15 | −27.96 |
| 60 | −0.01 | −3.98 | −12.34 |
| 50 | 0.00 | 0.00 | −0.01 |
| 40 | +0.01 | +3.64 | +11.80 |
| 30 | +2.01 | +10.65 | +26.59 |
| 20 | +8.00 | +20.07 | +47.91 |
| 10 | +16.99 | +36.73 | +84.27 |
And the other direction, for a few round strikes:
| Strike vs spot ($) | 15 s contract: Up worth (¢) | 1 min contract: Up worth (¢) | 5 min contract: Up worth (¢) |
|---|---|---|---|
| −50 | 98.9 | 94.0 | 80.4 |
| −25 | 94.5 | 83.3 | 68.3 |
| −10 | 82.6 | 68.5 | 58.1 |
| 0 | 41.4 | 47.3 | 49.4 |
| +10 | 17.0 | 30.8 | 41.3 |
| +25 | 5.4 | 16.3 | 31.0 |
| +50 | 1.1 | 5.9 | 19.1 |
Up at a strike equal to spot is worth less than 50¢ at short horizons, because Bitcoin's last trade is sometimes exactly unchanged: 17% of the time after 15 seconds, 5% after a minute, 0.5% after five. In a cents market that tie goes to one side by rule. On Rizon's BTC markets it's a push, and both sides get their money back.
A worked example
Bitcoin is at $83,000, and you think it'll rise over the next five minutes.
In a cents market with the price to beat at $83,000 and five minutes to go, Up's fair price is about 49¢. If the price to beat were $25 below the current price, still with five minutes to go, Up would be worth about 68¢: you'd pay 68¢ to make 32¢. Your view hasn't changed; the price has, because the strike stayed behind.
In a strike book you pay the same either way: $10 to get $20 back. You choose the strike. Up at $83,000 is about a coin flip (49.4% of 5-minute intervals finished above, 0.5% exactly at it). Up at $82,975 finished above 68.3% of the time, and up at $83,025 only 31.0%. If the book offers up at $83,005, you're buying a contract worth about 45¢ (strike +$5) for the equivalent of 50¢; if someone sells you up at $82,990, you're buying one worth about 58¢.
So the conversion rule is simple: a strike book's price in cents is the probability of finishing past its strike. Near spot, each dollar of strike is worth about 2.6¢ at 1 minute (between $0 and +$2) and 0.85¢ at 5 minutes (between $0 and +$4.50). That is also how to compare spreads across the two kinds of market: a spread of a few dollars of strike at 1 minute is several cents.
Why Rizon quotes strikes
- The contract you trade is always at the money. Each contract starts at your fill, so the strike starts next to the price. You never buy into a window that drifted to 84¢ before you arrived.
- One book per horizon. A cents market needs a strike, so it lists one market per window (or one per price range); a strike book is one continuous book for each horizon, and all the liquidity sits in it.
- It reads like a futures book. Price is the strike. Up is buying (bids), down is selling (asks); for a buyer a lower strike is better, for a seller a higher one. Your position is the strike you hold.
- You can see it. A strike is a level on the chart. On Rizon your position is a line at that strike and its expiry second, and you watch the price run toward it, and through it.
The cents view doesn't go away: it's the right way to think about what a strike is worth. A strike book just puts the number you can see, a price level, on the quote.
How we measured it
Binance BTCUSDT 1-second klines, daily archive, 27 Sep to 26 Oct 2026; every second as a start, about 2.59 million per horizon. "Worth" is the share of starts whose price h seconds later was strictly above the strike: a historical frequency over one month, not a forecast, and before any spread or fee. Rerun with bun studio/research/strike-vs-probability.ts in Rizon's repository.
FAQ
What does a price of 70¢ mean in a prediction market?
A share that pays $1 if it's right costs 70¢, so the market is pricing that outcome at about a 70% chance. You pay 70¢ to make 30¢.
What is a strike in an up/down contract?
The level the underlying has to finish above (for up) or below (for down) at expiry. In a fixed-window market it's the window's opening price, the price to beat. On Rizon it's the price on the book where you trade.
How do I convert a strike into a probability?
Use the distribution of moves over the contract's horizon: the probability is the share of moves that finish past the strike. Over 1 minute in October 2026, a Bitcoin strike $10 above spot finished above 30.8% of the time, so Up there was worth about 31¢.
Why does every Rizon contract pay 2×?
Because the price is fixed and the strike moves. Paying your size to get twice it back is the same as buying a $1 contract at 50¢; the book competes on the strike instead of the price.
What happens if Bitcoin finishes exactly at the strike?
On Rizon's Bitcoin markets it's a push: both sides get their size back. Rizon's Elon Musk post-count markets use strikes on half-posts, so they can't push.